The invention relates to a rotational damper of a motor vehicle, in particular for dampening a movement of an unsprung mass relative to a sprung mass.
The chassis serves for coupling the vehicle superstructure with the street. Beside transmitting the forces relevant for driving, a vertical degree of freedom enables adjustment of the comfort behavior and the driving safety. The vibration behavior between the vehicle superstructure and the wheel, with its wheel guiding elements, is determined by a spring element and a damper element. The spring element serves for statically holding the superstructure. Changes in lift of the spring are stored as spring energy. The damper element serves for absorbing vibration energy of the superstructure, the sprung mass and also of the wheel with wheel carrier, the unsprung mass. Hereby the vibration damper directly connects the sprung mass and the unsprung mass. In the state of the art the throttle effect of the hydraulic fluid generally acts as a force against the relative velocity between the sprung and unsprung mass.
In addition the state of the art includes DE 10 2011 101 350 A1 or DE 10 2011 101 701 DE, which disclose using electric or electromagnetic forces for generating the force. Common to both is the fact that sprung and unsprung masses are connected via the damper element and a mutual support between both is present. Beside the fact that the gyroscopic effect in the region of the chassis is to be used in an automobile, an innovation relative to the state of the art is the targeted adjustment and the exertion of moments in all directions at any desired point in time, of the axis of the precision moment.
From the state of the art, DE 60 2008 64T2, US 20040244513A1 and WO2011/100796A1, gyrostabilizers are known for stabilizing a ship, whose movement is caused by waves. These gyrostabilizers for example contain a first sensor system, which measures the precession of a flywheel, a control system which generates a control signal, and an actuator, which provides the flywheel with a precession moment. The exerted precession moment hereby acts as regulated counter moment so that no driving energy is acting on the flywheel. In addition in the case of a ship only a rolling movement is generated, which is to be stabilized by the device.
In this context the patent document EP 0650890B1 discloses a device for suppressing the vibration of an object. For this a control moment gyro is provided which includes a flywheel, which is connected with a first shaft rotatably supported in a gimbal, wherein the gimbal includes a second shaft rotatably supported in an object whose vibration is to be controlled.
An angular sensor for measuring the rotation of the object to be controlled about an axis, which is normal to the plane defined by the first and second shaft.
For vibration damping, a generator is provided on the second axle which brakes in dependence on the measured angular velocity of the third axle, wherein the flywheel is kept in rotation via a motor.
In gyros the effect of precession is known. When the rotation axis of a rotating body is changed, a force is generated which is perpendicular to the rotation axis and the deflection axis. This force is referred to as precession. In a cardanic suspension the interaction between the individual rotational speeds and moments is described by the dynamic Euler equationsMa=Jaa−(Jb−Jc)ωcωb  (1)Mb=Jbb−(Jc−Ja)ωaωc  (2)Mc=Jcc−(Ja−Jb)ωbωa  (3)in the body fixed coordinate system. Hereby the relationship dφi/dt−ωi and dωi/dt=i applies, wherein φi is the actual angular position of the respective shaft.